1. Welcome to the World of Chemistry
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2. The Language of Chemistry
The elements, their names, and symbols are given on the PERIODIC TABLE
How many elements are there?
117 elements have been identified
82 elements occur naturally on Earth
Examples: gold, aluminum, lead, oxygen, carbon
35 elements have been created by scientists
Examples: technetium, americium, seaborgium

3. The Periodic Table
Dmitri Mendeleev ( )

4. Glenn Seaborg (1912-1999) Discovered 8 new elements.
Only living person for whom an element was named.

5. Types of Observations and Measurements
We make QUALITATIVE observations of reactions — changes in color and physical state.
We also make QUANTITATIVE MEASUREMENTS, which involve numbers.
Use SI units — based on the metric system

6. Chemistry In Action
On 9/23/99, $125,000,000 Mars Climate Orbiter entered Mars’ atmosphere 100 km lower than planned and was destroyed by heat.
1 lb = 1 N
1 lb = 4.45 N
“This is going to be the cautionary tale that will be embedded into introduction to the metric system in elementary school, high school, and college science courses till the end of time.”

7. Standards of Measurement
When we measure, we use a measuring tool to compare some dimension of an object to a standard.
For example, at one time the standard for length was the king’s foot. What are some problems with this standard?

8. What is Scientific Notation?
Scientific notation is a way of expressing really big numbers or really small numbers.
For very large and very small numbers, scientific notation is more concise.

9. Scientific notation consists of two parts:
A number between 1 and 10
A power of 10
N x 10x

10. To change standard form to scientific notation…
Step 1: Place the decimal point so that there is 1 non-zero digit to the left of the decimal point.
Step 2: Count the number of decimal places the decimal point has “moved” from the original number. This will be the exponent on the 10.
Step 3: If the original number was less than 1, then the exponent is negative. If the original number was greater than 1, then the exponent is positive.

11. Examples Given: 289,800,000 Use: 2.898 (moved 8 places)
Answer: x 108
Given:
Use: 5.67 (moved 4 places)
Answer: 5.67 x 10-4

12. To change scientific notation to standard form…
Simply move the decimal point to the right for positive exponent 10.
Move the decimal point to the left for negative exponent 10.
(Use zeros to fill in places.)

13. Answer: 5,093,000 (moved 6 places to the right)
Example
Given: x 106
Answer: 5,093,000 (moved 6 places to the right)
Given: x 10- 4
Answer: (moved 4 places to the left)

14. Learning Check Express these numbers in Scientific Notation: 405789 2
4.1 x 105
3.9 x 10 -3
2.0 x 100
4.8 x 10-1

15. In every measurement there is a Number followed by a
Stating a Measurement
In every measurement there is a
Number followed by a
Unit from a measuring device
The number should also be as precise as the measurement!

16. UNITS OF MEASUREMENT Use SI units — based on the metric system Length
Mass
Volume
Time
Temperature
Meter, m
Kilogram, kg
Liter, L
Seconds, s
Celsius degrees, ˚C
kelvins, K

17. Learning Check M L M V Match L) length M) mass V) volume
____ A. A bag of tomatoes is 4.6 kg.
____ B. A person is 2.0 m tall.
____ C. A medication contains 0.50 g Aspirin.
____ D. A bottle contains 1.5 L of water. M L M V

18. Metric Prefixes Kilo- means 1000 of that unit
1 kilometer (km) = meters (m)
Centi- means 1/100 of that unit
1 meter (m) = 100 centimeters (cm)
Milli- means 1/1000 of that unit
1 Liter (L) = milliliters (mL)

19. Metric Prefixes

20. Learning Check 1. 1000 m = 1 ___ a) mm b) km c) dm
g = 1 ___ a) mg b) kg c) dg
L = 1 ___ a) mL b) cL c) dL
m = 1 ___ a) mm b) cm c) dm

21. Conversion Factors
Fractions in which the numerator and denominator are EQUAL quantities expressed in different units
Example: in. = 2.54 cm
Factors: 1 in and cm
2.54 cm in.

22. Learning Check 1. Liters and mL 2. Hours and minutes
Write conversion factors that relate each of the following pairs of units:
1. Liters and mL
2. Hours and minutes
3. Meters and kilometers

23. How many minutes are in 2.5 hours?
Conversion factor
2.5 hr x min = min
1 hr
cancel
By using dimensional analysis / factor-label method, the UNITS ensure that you have the conversion right side up, and the UNITS are calculated as well as the numbers!

24. Steps to Problem Solving
Write down the given amount. Don’t forget the units!
Multiply by a fraction.
Use the fraction as a conversion factor. Determine if the top or the bottom should be the same unit as the given so that it will cancel.
Put a unit on the opposite side that will be the new unit. If you don’t know a conversion between those units directly, use one that you do know that is a step toward the one you want at the end.
Insert the numbers on the conversion so that the top and the bottom amounts are EQUAL, but in different units.
Multiply and divide the units (Cancel).
If the units are not the ones you want for your answer, make more conversions until you reach that point.
Multiply and divide the numbers. Don’t forget “Please Excuse My Dear Aunt Sally”! (order of operations)

25. Learning Check a) 2440 cm b) 244 cm c) 24.4 cm
A rattlesnake is 2.44 m long. How long is the snake in cm?
a) cm
b) 244 cm
c) 24.4 cm

26. Solution
A rattlesnake is 2.44 m long. How long is the snake in cm?
b) 244 cm
2.44 m x cm = 244 cm
1 m

27. How many seconds are in 1.4 days? Unit plan: days hr min seconds
Learning Check
How many seconds are in 1.4 days?
Unit plan: days hr min seconds
1.4 days x 24 hr x ??
1 day

28. Wait a minute!
What is wrong with the following setup?
1.4 day x 1 day x min x 60 sec
24 hr hr min

29. = 3.5 feet / second Dealing with Two Units
If your pace on a treadmill is 65 meters per minute, how many feet per second is this?
65 meters
3.28 feet
1 minute
1 minute
1 meter
60 seconds
= 3.5 feet / second

30. Temperature Scales Fahrenheit Celsius Kelvin Anders Celsius 1701-1744
Lord Kelvin
(William Thomson)

31. Temperature Scales Fahrenheit Celsius Kelvin 32 ˚F 212 ˚F 180˚F 100 ˚C
Boiling point of water
32 ˚F
212 ˚F
180˚F
100 ˚C
0 ˚C
100˚C
373 K
273 K
100 K
Freezing point of water

32. Calculations Using Temperature
Generally require temp’s in kelvins
T (K) = t (˚C)
Body temp = 37 ˚C = 310 K
Liquid nitrogen = ˚C = 77 K

33. Can you hit the bull's-eye?
Three targets with three arrows each to shoot.
How do they compare?
Both accurate and precise
Precise but not accurate
Neither accurate nor precise
Can you define accuracy and precision?

34. Significant Figures
The numbers reported in a measurement are limited by the measuring tool
Significant figures in a measurement include the known digits plus one estimated digit

35. Counting Significant Figures
RULE 1. All non-zero digits in a measured number are significant. Only a zero could indicate that rounding occurred.
Number of Significant Figures
38.15 cm 4
5.6 ft 2
65.6 lb ___
m ___

36. Leading Zeros
RULE 2. Leading zeros in decimal numbers are NOT significant.
Number of Significant Figures
0.008 mm 1
oz 3
lb ____
mL ____

37. Sandwiched Zeros
RULE 3. Zeros between nonzero numbers are significant. (They can not be rounded unless they are on an end of a number.)
Number of Significant Figures
50.8 mm 3
2001 min 4
0.702 lb ____
m ____

38. Trailing Zeros 25,000 in. 2 200. yr 3 48,600 gal ____
RULE 4. Trailing zeros in numbers without decimals are NOT significant. They are only serving as place holders.
Number of Significant Figures
25,000 in. 2
200. yr 3
48,600 gal ____
25,005,000 g ____

39. Learning Check A. Which answers contain 3 significant figures?
1) ) ) 4760
B. All the zeros are significant in
1) ) ) x 103
C. 534,675 rounded to 3 significant figures is
1) ) 535, ) 5.35 x 105

40. Learning Check
State the number of significant figures in each of the following:
A m
B L
C g
D m

41. Adding and Subtracting
The answer has the same number of decimal places as the measurement with the fewest decimal places.
one decimal place
two decimal places
26.54
answer one decimal place

42. Learning Check
In each calculation, round the answer to the correct number of significant figures.
A =
1) ) ) 257
B =
1) ) ) 40.7

43. Multiplying and Dividing
Round (or add zeros) to the calculated answer until you have the same number of significant figures as the measurement with the fewest significant figures.

44. Learning Check
A X 4.2 =
1) ) )
B ÷ =
1) ) ) 60

45. Reading a Meterstick
. l I I I I cm
First digit (known) = ?? cm
Second digit (known) = ? cm
Third digit (estimated) between
Length reported = cm
or cm
or cm

46. Known + Estimated Digits
In 2.76 cm…
Known digits 2 and 7 are 100% certain
The third digit 6 is estimated (uncertain)
In the reported length, all three digits (2.76 cm) are significant including the estimated one

47. Zero as a Measured Number
. l I I I I cm
What is the length of the line?
First digit ?? cm
Second digit ? cm
Last (estimated) digit is cm

48. Always estimate ONE place past the smallest mark!

49. DENSITY - an important and useful physical property
Aluminum
Platinum
Mercury
13.6 g/cm3
21.5 g/cm3
2.7 g/cm3

50. PROBLEM: Mercury (Hg) has a density of 13. 6 g/cm3
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg in grams? In pounds?

51. 1. Use density to calc. mass (g) from volume.
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg?
First, note that 1 cm3 = 1 mL
Strategy
1. Use density to calc. mass (g) from volume.
2. Convert mass (g) to mass (lb)
Need to know conversion factor
= 454 g / 1 lb

52. 2. Convert mass (g) to mass (lb)
PROBLEM: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg?
1. Calculate mass using density equation
2. Convert mass (g) to mass (lb)

53. Volume Displacement 25 mL
A solid displaces a matching volume of water when the solid is placed in water.
33 mL
25 mL

54. Learning Check
What is the density (g/cm3) of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL?
1) 0.2 g/ cm ) 6 g/m ) g/cm3
33 mL
25 mL

55. Learning Check
If blood has a density of 1.05 g/mL, how many liters of blood are donated if 575 g of blood are given?
1) L
2) L
3) L

56. Scientific Method State the problem clearly. Gather information.
Form a _hypothesis_.
Test the hypothesis.
Evaluate the data to form a conclusion.
If the conclusion is valid, then it becomes a theory. If the theory is found to be true over along period of time (usually 20+ years) with no counter examples, it may be considered a law.
6. Share the results.

57. Graphing Why do we Graph Data?
To show the relationship between the graphed variables
To gain interpolated and extrapolated data
‘inter’ – in between the data points
‘extra’ – outside the data points

58. Independent & Dependent Variables
The Dependent Variable is always assigned to the y-axis
Relies on the changes in the independent variable.
The dependent variable is what we measure.
The independent variable is always assigned to the x-axis
Does not rely on another variable.